ISO mountain biking club for 10 yo (non-competitive)

My 10 year old son is very interested in mountain biking and is a solid beginner. I'm looking for a club/team for his age but am only finding ones for middle and high schoolers. Any tips? He wants to learn more technical skills (and I'd like him to learn safety skills!) Ideally something in the vicinity of Berkeley / El Cerrito / Orinda / Pinole.

thanks so much!